Watch fastener



FIG. 1 is a perspective view of our claimed design;

FIG. 2 is a side perspective thereof, with the opposite side being a mirror image;

FIG. 3 is a top view thereof; and,

FIG. 4 is a bottom view thereof.

The broken lines are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a watch fastener, as shown and described. 